Atomizing devices for liquid fuel

ABSTRACT

In the end portion of a fuel-atomization nozzle in which the fuel passage contains at its end pressure-atomization means as well as an end opening for atomization by ultrasonic vibration of the nozzle, the pressure-atomization means include a swirl plug having helical passages and, spaced from it by a swirl chamber, an orifice disc containing a final orifice of smaller diameter than the plug. Both the plug and the disc are secured in a larger-diameter counter-bore at the end of the fuel passage. They are secured in the counter-bore by electron-beam welding, the plug by radial spot welding through the wall, and the disc by a circumferential weld, which also forms seal closing the ends of the counter-bore.

tilted States Patent [191 Goodinge et a1.

[ ATOMIZING DEVICES FOR LIQUID FUEL [75 Inventors: Mark WallingerGoodinge,

Brentwood; Norman Moss, llford, both of England [73] Assignee: PlesseyHandel und Investments A.G., Zug, Switzerland [22] Filed: June 27, 1972[21] App]. No.: 266,778

[30] Foreign Application Priority Data June 29, 1971 Great Britain30,370/71 [52] 11.8. C1 239/102, 239/463, 239/494, 239/501, 239/600 [51]Int. Cl 1305b l/34, BOSb 1/O8, B05b 17/06 [58] Field of Search 239/4,102, 463, 239/468, 469, 470, 474, 491, 494, 500, 501, 596, 600

[56] References Cited UNITED STATES PATENTS 2,110,365 3/1938 lmfeld239/474 2,284,264 5/1942 Crisp 239/494 X 2,981,483 4/1961 Pichon 239/491X 3,092,330 6/1963 Ridenour et a1. 239/463 X 3,200,873 8/1965 Young eta1. 239/102 X 3,214,101 10/1965 Perron 239/4 X 3,275,059 9/1966McCullough 239/4 X 3,317,139 5/1967 Freeland 239/4 X .Ian. 8, 1974Rrimary Examiner-Robert S. Ward, Jr. A

Atlorhe y BTurn, Moscovitiil riedrnan & Kaplan [5 7] ABSTRACT In the endportion of a fuel-atomization nozzle in which the fuel passage containsat its end pressureatomization means as well as an end opening foratomization by ultrasonic vibration of the nozzle, thepressure-atomization means include a swirl plug having helical passagesand, spaced from it by a swirl chamber, an orifice disc containing afinal orifice of smaller diameter than the plug. Both the plug and thedisc are secured in a larger-diameter counter-bore at the end of thefuel passage. They are secured in the counter-bore by electron-beamwelding, the plug by radial spot welding through the wall, and the discby a circumferential weld, which also forms seal closing the ends of thecounter-bore.

5 Claims, 2 Drawing Figures 1 ATOMIZING DEVICES FOR LIQUID FUEL Thisinvention relates to atomizing devices for liquid fuel and moreparticularly but not exclusively to liquid fuel burners for gas-turbineengines. Our co-pending British Patent specification No. 1,289,341describes a gas-turbine engine having a fuel burner equipped with aninjection device for liquid fuel wherein a passage for fuel underpressure terminates in an open orifice provided with apressure-atomization nozzle, and an ultrasonic vibrator is so connectedwith the nozzle as to vibrate, when operative, the nozzle in the axialdirection of the nozzle. The present invention has for an object toprovide an improved nozzle arrangement terminating in an open orificeand it provides a pressureatomization nozzle which is connected to suchultrasonic vibrator, for applying longitudinal vibrations to the nozzle,and wherein the nozzle is provided with helical swirl passages whichproduce circulation of the flow of fuel injected through a nozzle, and amore specific object of the invention is to provide an improvedconstruction of such an arrangement, which will satisfactorily withstandfor long periods the mechanical effect of the ultrasonic vibrations. Theswirl passages of the swirl nozzle are preferably formed in a plug whichis secured in a counter-bore at the end of the fuel passage of thenozzle.

The securing of this plug must withstand very considerable forces whenthe nozzle is subjected to ultrasonic vibrations, and according to asubsidiary feature of the invention, the necessary mechanical strengthis obtained by spot-welding the plug in position through the wall of thepassage, preferably by so-called electronbeam spot welding. This methodof securing a plug provided with swirl passages in a longitudinal boreof a stepped-horn vibration transformer constitutes another aspect ofthe invention. The swirl passages are preferably formed as open groovesin the circumference of the plug, which co-operates with the wallsurface of the counter-bore when the plug is inserted, and in order tofacilitate manufacture, a number of spot-welds is preferably employedwhich differs from the number of the grooves so as to ensure that if oneof the spot-welds faces one of the grooves and is therefore liable toblock that particular groove, the other spot welds are positioned clearof the other grooves. In a typical case, four swirl grooves and threespot welds, all uniformly spaced round the circumference, may beemployed.

The final orifice is preferably arranged in an orifice disc which isfitted into the end of the counter-bore and which is axially spaced fromthe outer end of the swirl plug so that the interposed part of thelength of the counter-bore provides a swirl chamber between the end ofthe swirl plug and the disc containing the final orifice. The latterdisc is preferably secured in the counter-bore by seam welding,preferably by electronbeam seam welding, with the electron beam appliedin the axial direction so as to form a welded seam round thecircumference of the orifice disc, thus ensuring sealing of the orificedisc in the counterbore as well as mechanically fixing it to the nozzlebody.

In order that the invention may be more readily understood, referencewill now be made to the accompanying drawing, in which FIG. 1 is anelevation showing the general construction of one form of atomizernozzle according to the present invention, and

FIG. 2 is an elevation, drawn to a larger scale and partly in axialsection, showing the end portion of the nozzle including the fuelpassage, the swirl plug and the final-orifice disc.

Referring now to the drawings, the atomizing device illustratedcomprises a stepped horn member 1 and a balance member 2, which areattached adhesively or by any other means to the opposite sides,respectively, of a piezoelectric-disc transducer 3, so that the latterwill produce ultrasonic vibrations of the members 1 and 2 towards andaway from each other when it is energised by the application of analternating voltage of ultrasonic frequency to a pair of terminals 4, 5.The transducer 3 will transmit the ultrasonic vibrations on the one handto the balance member 2 and on the other hand to the stepped hornmember 1. The reduceddiameter horn portion 6 of the latter acts toincrease the amplitude of the vibrations that appear at its outer end. Afuel passage 7 for the fuel to be ejected extends longitudinally throughthe horn portion 6 and leads the fuel to the opening 8a of an orificedisc 8, which the fuel reaches after passing through helical passagesconstituted by open grooves 9 in a cylindrical swirl plug 10. At itsinlet end the passage 7 is joined by a radial passage 11, which isarranged in a plane central to the length of the transducer 3, and whichserves for connection to an external fuel line 12; being arranged in thetransverse plane of symmetry of the transducer 3, the radial passage 11and the line 12 remain unaffected by the ultrasonic vibrations.

As will be seen more clearly, in FIG. 2, the outer end of the passage 7is enlarged by the provision of a counter-bore 13, in which the swirlplug 10 provided with the grooves 9 forming the helical passages, andthe orifice disc 8 which contains final orifice 8a, are secured inaxially spaced relation so as to leave between them a swirl chamber 14.The plug 10 is also spaced from the bottom of the counter-bore 13 toprovide, between the end of the small-diameter passage 7 proper and thelarger-diameter plug 10, a distribution chamber 15 in which the flow offuel from the passage 7 can spread in order to reach the helical grooves9.

It is important that the swirl plug 10 and the disc 8 should each befirmly held in position because they have to withstand the action ofultrasonic vibration of the horn portion 6, and we have found that thiscan be achieved very satisfactorily by spot-welding the plug 10 to thewall of the counter-bore 13 with the help of electron beams appliedradially to the outer surface of the horn portion 6 as indicated by thearrow Y. To ensure reliable operation of the swirler passages 9, it isnecessary to ensure that at least the majority of these passages are notobstructed by the spot-welding operation, and while this could beachieved by a careful check on the angular position of the plug 10 aboutits axis in relation to the points at which spot welding is effected, wehave found that such a check is generally unnecessary if the welds areuniformly spaced round the circumference and the number of weldsemployed differs in such manner from the number of swirl grooves 9 as toensure that if one of the welds should be substantially in line with oneof the swirl grooves 9, the other swirl grooves 9 will be clear of anywelding spots. Thus it has been assumed in the illustrated example thatthree spot welds, uniformly distributed round the circumference of thehorn portion 6, are used for securing a swirl plug 10 having four swirlgrooves 9. The orifice disc 8,

which contains the final orifice 8a, is also secured in position in thecounter-bore 13 by electron-beam welding, but in this case the electronbeam is applied in an axial direction at the circumference of the disc8, as indicated by the arrow X. The weld produced extends continuouslyround the whole of the circumference of the disc 8 and thus ensures aneffective seal between the circumference of the disc 8 and the wall ofthe counter-bore 13, as well as securing the disc 8 in position.

What we claim is:

1. An atomizing device for liquid fuel, comprising: an ultrasonicvibrator; a velocity-transformer body of the stepped-horn type havingone end attached to the vibrator, said body having a bore extendingalong the axis thereof from the other end of said body and including afirst portion, remote from said other end, and an adjoining secondportion connecting said first portion to the said other end and being oflarger diameter than said first portion; a swirl plug having acylindrical external surface that is provided with helical groovesextending from one end to the other of said surface, said plug havingsubstantially the same diameter as, and being coaxially accommodated in,said second portion of the bore with the end of the plug at a distancefrom the said other end of the transformer body, and being secured inposition in said bore by a weld connecting at least some points on thecircumference of the plug and the wall of the bore; and an end-wallmember having a central orifice of a diameter substantially smaller thanthe diameter of said second portion of the bore, said endwall memberbeing sealingly secured to the transformer body by a weld, in a positionin which said orifice is aligned with the bore, and in which the endmember closes, apart from said orifice, the outer end of the bore and toface the adjacent end of the swirl plug at an axial distance therefrom.

2. A device as claimed in claim 1, wherein the swirl plug is secured inthe bore by spot welds that join circumferentially spaced points on theplug to the wall of the bore.

3. A device as claimed in claim 2, wherein a plurality of helicalgrooves are uniformly spaced round the plug, and a number of spot weldsare also uniformly spaced round the plug, the number of said spot weldsbeing prime to the number of said grooves.

4. A device as claimed in claim 2, wherein said endwall member issecured to the transformer body by an endless seam weld. v

5. A device as claimed in claim 1, wherein said endwall member is a discfitting into the end of said bore adjacent to said other end of thevelocity transformer and is secured to the wall of the bore by anendless

1. An atomizing device for liquid fuel, comprising: an ultrasonicvibrator; a velocity-transformer body of the steppedhorn type having oneend attached to the vibrator, said body having a bore extending alongthe axis thereof from the other end of said body and including a firstportion, remote from said other end, and an adjoining second portionconnecting said first portion to the said other end and being of largerdiameter than said first portion; a swirl plug having a cylindricalexternal surface that is provided with helical grooves extending fromone end to the other of said surface, said plug having substantially thesame diameter as, and being coaxially accommodated in, said secondportion of the bore with the end of the plug at a distance from the saidother end of the transformer body, and being secured in position in saidbore by a weld connecting at least some points on the circumference ofthe plug and the wall of the bore; and an end-wall member having acentral orifice of a diameter substantially smaller than the diameter ofsaid second portion of the bore, said end-wall member being sealinglysecured to the transformer body by a weld, in a position in which saidorifice is aligned with the bore, and in which the end member closes,apart from said orifice, the outer end of the bore and to face theadjacent end of the swirl plug at an axial distance therefrom.
 2. Adevice as claimed in claim 1, wherein the swirl plug is secured in thebore by spot welds that join circumferentially spaced points on the plugto the wall of the bore.
 3. A device as claimed in claim 2, wherein aplurality of helical grooves are uniformly spaced round the plug, and anumber of spot welds are also uniformly spaced round the plug, thenumber of said spot welds being prime to the number of said grooves. 4.A device as claimed in claim 2, wherein said end-wall member is securedto the transformer body by an endless seam weld.
 5. A device as claimedin claim 1, wherein said end-wall member is a disc fitting into the endof said bore adjacent to said other end of the velocity transformer andis secured to the wall of the bore by an endless seam weld.